Two groups of Chinese four-year-olds and their parents' interaction in joint activities were analyzed and compared. The children in Group 1 were high scorers in written number skills and the children in Group 2 were low scorers. Eighty-five dyads participated in four separate 15-minute joint activities such as book reading, mathematical work sheets, blank paper and blocks. A mini-questionnaire was also administered. The results indicated that a wide variety of mathematics and interactive strategies were involved in the activities, that there was no difference in the frequency of mathematical events occurring in the activities between the two groups, that more parents in Group 1 used several more positive strategies than the parents in Group 2, that more children in Group 2 had trouble remaining engaged in the activity, and that the frequency and the quality of parent-child joint activities at home, such as book reading and mathematical work sheets, were possible contributors to children's development of mathematics. (Contains 5 tables.)